Various blood pumps are known for pumping the blood of a patient to provide assistance to his/her ailing heart. Particularly, implantable, magnetically driven, rotary ventricular assist devices (VADs) are blood pumps which may, if desired, be implanted in the patient to provide assistance in pumping blood for hearts that are afflicted with congestive heart failure or the like.
Axial flow pumps for blood have the advantage of narrow width, as compared to radial flow pumps. Typically, an axial flow pump has a cylindrical housing with an inlet, an outlet, and a rotor within the housing having impeller blades attached to the rotor. A set of electrical coils is disposed around the housing to provide a rotating magnetic field which spins the rotor. As the rotor rotates, the impeller blades propel the fluid (e.g., blood) through the inlet of the pump and out of the outlet. Radial flow pumps, such as the HVAD® pump of HeartWare, Inc., the Applicant, also have applicability in pumping blood for patients afflicted with congestive heart failure or the like.
Known axial flow pumps for blood have typically been made of suitable biocompatible metals, such as titanium. Generally, the pump is not inherently sealed. Stated another way, pumps of the prior art typically include separate components that require sealing (e.g., through the use of O-rings or other sealing devices) to attempt to establish a sealed environment around the coils. An example of such a prior art pump is shown in FIGS. 5A-C. Joining of components is not always fully effective and is, in some cases, subject to failure. In addition, the multitude of components makes for a difficult and expensive assembly of the pump since there are multiple seal points to establish.
In particular reference to the pump 120 of FIGS. 5A-C, as can be seen the pump includes a variety of components that require assembly. For instance, as shown in FIG. 5C, the pump includes upper and lower volute portions 130, 132, a metal casing 134, a tubular housing 136, a stator 138, and a rotor 140. Various sealing rings 142 are also provided. In its assembled form as shown in FIGS. 5A-B, the various parts mentioned above must be pieced together and, in many cases, certain parts are adhered or connected together in some manner. For instance, stator 138 is adhered to tubular housing 136 and an epoxy backfill is used to secure stator 138 to metal casing 134 during assembly. Further, sealing rings 142 are utilized in an effort to create a sealed environment for pump 120. Assembly of pump 120 therefore requires a number of pieces and occupies time and effort to ensure pump 120 operates in a sealed environment.